test: use custom wait for watching/helpers.sh

This allows the fs-memo.t test to succeed on Nix. Before the pid of Dune
was being thrown away by a bash bug causing wait to think it was not a
child process and rejecting it. We therefore wait instead for all child
processes.

Signed-off-by: Ali Caglayan <alizter@gmail.com>

test/blackbox-tests/test-cases/watching/helpers.sh

@@ -22,7 +22,16 @@ with_timeout () {
 
 stop_dune () {
     with_timeout dune shutdown;
-    wait $DUNE_PID;
+    # On Linux, we may run into a bash pid aliasing bug that causes wait to
+    # reject the pid. Therefore we wait for all child processes instead.
+    if [ "$(uname -s)" = "Linux" ]
+    then
+        # wait for all child processes
+        wait $(jobs -p);
+    else
+        # wait for dune to exit
+        wait $DUNE_PID;
+    fi
     cat .#dune-output;
 }